Dyeing composition for keratinous fibers comprising a dicationic diazo dye

ABSTRACT

The present disclosure relates to a novel dyeing composition for dyeing human keratinous fibers, such as hair, comprising at least one dicationic diazo dye of formula (I):
 
[W 1 —N═N—W 2 —W 3 —(W 4 —W 5 ) p -] 2 -L   Formula (I)
 
as well as the process for dyeing hair using same. Certain compounds of formula (I) are also disclosed herein.

FIELD OF THE INVENTION

The invention relates to a novel dye composition for dyeing humankeratin fibers, in particular the hair, comprising a particulardicationic diazo dye, and also to the process for dyeing keratin fibersusing such a composition. The invention also relates to novel dicationicdiazo dyes.

BACKGROUND OF THE INVENTION

It is known practice to dye keratin fibers, and in particular humanhair, with dye compositions containing oxidation dye precursors, whichare generally known as oxidation bases, such as ortho- orpara-phenylenediamines, ortho- or para-aminophenols and heterocycliccompounds. These oxidation bases are colorless or weakly coloredcompounds, which, when combined with oxidizing products, give rise tocolored compounds by a process of oxidative condensation.

It is also known that the shades obtained with these oxidation bases maybe varied by combining them with couplers or coloration modifiers, thelatter agents being chosen especially from aromatic meta-diamines,meta-aminophenols, meta-diphenols and certain heterocyclic compoundssuch as indole compounds.

The variety of molecules used as oxidation bases and couplers allows awide range of colors to be obtained.

This process of oxidation dyeing consists in applying to the keratinfibers oxidation bases or a mixture of oxidation bases and of couplerswith an oxidizing agent, for example aqueous hydrogen peroxide solution,leaving the application on the fibers, and then rinsing the fibers. Thecolorations resulting therefrom are permanent, strong and fast withrespect to external agents, especially light, bad weather, washing,perspiration and rubbing. Generally applied at basic pH, dyeing andsimultaneous lightening of the fiber may be obtained, which is reflectedin practice by the possibility of obtaining a final coloration that islighter than the original color. In addition, lightening of the fibermay have the advantageous effect of producing a unified color in thecase of gray hair, and, in the case of naturally pigmented hair, ofbringing out the color, i.e. of making it more visible.

It is also known practice to dye keratin fibers by direct dyeing. Theprocess conventionally used in direct dyeing consists in applying to thekeratin fibers direct dyes, which are colored and coloring moleculesthat have affinity for the fibers, leaving the dyes on the fibers, andthen rinsing the fibers.

It is known practice, for example, to use direct dyes belonging to thenitrobenzene, anthraquinone, nitropyridine, azo, indoamine, azine ortriarylmethane class.

The colorations resulting therefrom are particularly chromaticcolorations, that are temporary or semi-permanent since the nature ofthe interactions binding the direct dyes to the keratin fiber, and theirdesorption from the surface and/or the core of the fiber are responsiblefor their poor dyeing power and their poor resistance to washing or toperspiration. These direct dyes are also generally light-sensitive dueto the poor resistance of the chromophore with respect to photochemicalattack, leading over time to fading of the coloration of the hair. Inaddition, their light sensitivity is dependent on their uniformdistribution or distribution as aggregates in the keratin fiber.

It is known practice to use direct dyes in combination with oxidizingagents. However, direct dyes are generally sensitive to the action ofoxidizing agents such as aqueous hydrogen peroxide solution, andreducing agents such as sodium bisulfite, which makes it generallydifficult to use them in compositions for lightening direct dyeing basedon aqueous hydrogen peroxide solution and based on a basifying agent orin oxidation dye compositions in combination with precursors such asoxidation bases or couplers.

For example, it has been proposed in patent applications FR-1 584 965and JP-062 711 435 to dye the hair with dye compositions based on nitrodirect dyes and/or dispersed azo dyes and on ammoniacal aqueous hydrogenperoxide solution, by applying to the hair a mixture of said dyes and ofsaid oxidizing agent, prepared just before use. However, the colorationsobtained are found to have insufficient resistance and disappear onshampooing, making the lightening of the hair fiber show through. Such acoloration becomes unattractive by changing over time.

It has also been proposed in patent applications JP-53 95693 and JP-55022 638 to dye the hair with compositions based on cationic direct dyesof oxazine type and on ammoniacal aqueous hydrogen peroxide solution, byapplying to the hair ammoniacal aqueous hydrogen peroxide solution in afirst step, followed by a composition based on the oxazine direct dye ina second step. This coloration is unsatisfactory because it requires aprocess that is made too slow by the leave-in times of the twosuccessive steps. If, besides that, an extemporaneous mixture of theoxazine direct dye with ammoniacal aqueous hydrogen peroxide solution isapplied to the hair, the hair fiber is not colored or at most, avirtually nonexistent coloration is obtained.

More recently, patent application FR 2 741 798 has disclosed dyecompositions containing direct dyes comprising at least one quaternizednitrogen atom of the azo or azomethine type, said compositions being forextemporaneous mixing at basic pH with an oxidizing composition. Thesecompositions make it possible to obtain uniform, resistant and brightcolorations with glints. However, they do not allow keratin fibers to bedyed as strongly as with oxidation dye compositions.

There is thus a real need to find chromatic direct dyes that allowkeratin fibers to be dyed as strongly as with oxidation dyes, which arejust as stable as oxidation dyes to light, which are also fast withrespect to bad weather, washing and perspiration, and which are alsostable enough in the presence of oxidizing and reducing agents to beable simultaneously to obtain lightening of the fiber either by usinglightening direct compositions containing them, or by using oxidationdye compositions containing them. There is also a real need to finddirect dyes that allow keratin fibers to be dyed to obtain a very widerange of colors, in particular very chromatic colors, not forgetting the“fundamental” shades, for instance, blacks and browns.

DETAILED DESCRIPTION OF THE INVENTION

These aims are achieved with the present invention, one subject of whichis a composition for dyeing human keratin fibers, and in particular thehair, comprising at least one dicationic diazo dye of formula (I) below:[W₁—N═N—W₂—W₃—(W₄—W₅)_(p)-]₂-L  Formula (I)in which

-   -   p=0 or 1,    -   W₁ represents a heteroaromatic radical of formulae (II)        and (III) below:

-   -   W₂ represents a carbon-based, pyridine-based or pyridazine-based        aromatic group of formula (IV) below:

-   -   W₃ and W₅ represent, independently of each other, a radical        —NR₁₄— or an oxygen atom —O—, or a nitrogen atom,    -   W₄ represents a saturated or unsaturated, linear or branched        C₁-C₁₆ hydrocarbon-based chain, which can form one or more 3- to        6-membered carbon-based rings, one or more carbon atoms of the        carbon-based chain of which may be replaced with an oxygen,        nitrogen or sulfur atom or with an SO₂ group, and the carbon        atoms of which may be substituted, independently of each other,        with one or more halogen atoms, W₄ not comprising a peroxide        bond or diazo or nitroso radicals; a piperazine ring; a group of        formula (V) below:

in which formulae (II), (III), (IV) and (V):

-   -   X₁ represents a nitrogen atom or a radical CR₅    -   X₂ represents a nitrogen atom or a radical CR₆    -   X₃ represents a nitrogen atom or a radical CR₁₇    -   X₄ represents a nitrogen atom or a radical CR₁₈    -   Z₁ represents an oxygen or sulfur atom or a radical NR₈,    -   Z₂ represents a nitrogen atom or a radical CR₉,    -   it being understood that formula (II) does not denote an        imidazolium ring, i.e. (Z₁, Z₂) is different than (NR₈, CR₉),    -   Z₃ represents a nitrogen atom or a radical CR₁₂,    -   Z₄ represents a nitrogen atom or a radical CR₁₃,    -   the bond a of the 5-membered cationic ring of formula (II) is        linked to the azo group of formula (I),    -   the bond b of the 6-membered cationic ring of formula (III) is        linked to the azo group of formula (I),    -   when p=0,    -   then L represents a linear or branched, saturated C₁-C₁₆        hydrocarbon-based chain, which can form one or more 3- to        6-membered carbon-based rings, one or more carbon atoms of the        carbon-based chain of which may be replaced with an oxygen,        nitrogen or sulfur atom or with an SO₂ group, and the carbon        atoms of which may be substituted, independently of each other,        with one or more halogen atoms; L not comprising a peroxide bond        or diazo or nitroso radicals,    -   when p=1,    -   then L represents a saturated or unsaturated, linear or branched        C₁-C₁₆ hydrocarbon-based chain, which can form one or more 3- to        6-membered carbon-based rings, one or more carbon atoms of the        carbon-based chain of which may be replaced with an oxygen,        nitrogen or sulfur atom or with an SO₂ group, and not comprising        a peroxide bond or diazo or nitroso radicals,    -   R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂, R₁₃, R₁₄, R₁₅, R₁₆, R₁₇        and R₁₈ represent, together or independently of each other, a        hydrogen atom, a saturated or unsaturated, linear or branched        C₁-C₁₆ hydrocarbon-based chain, which can form one or more 3- to        6-membered carbon-based rings, one or more carbon atoms of the        carbon-based chain of which may be replaced with an oxygen,        nitrogen or sulfur atom or with an SO₂ group, and the carbon        atoms of which may be substituted, independently of each other,        with one or more halogen atoms; R₃, R₄, R₅, R₆, R₇, R₉, R₁₀,        R₁₁, R₁₂, R₁₃, R₁₄, R₁₅, R₁₆, R₁₇ and R₁₈ not comprising a        peroxide bond or diazo or nitroso radicals,    -   R₃ with R₄, R₇ with R₉, R₁₀ with R₁₁, R₁₂ with R₁₃ and R₁₅ with        R₁₆ may form a carbon-based aromatic ring, such as a phenyl,    -   X is an organic or mineral anion.

According to the invention, when it is indicated that one or more of thecarbon atoms of the hydrocarbon-based chain defined for the radicals L,R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂, R₁₃, R₁₄, R₁₅, R₁₆, R₁₇ and R₁₈may be replaced with an oxygen, nitrogen or sulfur atom or with an SO₂group, and/or when these hydrocarbon-based chains are unsaturated, thismeans that the following conversions may be performed, for example:

In particular the term “branched hydrocarbon-based chain” means a chainthat can form one or more 3- to 6-membered carbon-based rings. The term“unsaturated hydrocarbon-based chain” means a chain that may compriseone or more double bonds and/or one or more triple bonds, thishydrocarbon-based chain possibly leading to aromatic groups.

X is an organic or mineral anion chosen, for example, from a halide suchas chloride, bromide, fluoride or iodide; a hydroxide; a sulfate; ahydrogen sulfate; a (C₁-C₆)alkyl sulfate, for example a methyl sulfateor an ethyl sulfate; an acetate; a tartrate; an oxalate; a(C₁-C₆)alkylsulfonate such as methylsulfonate; an arylsulfonate that isunsubstituted or substituted with a C₁-C₄ alkyl radical, for instance a4-tolylsulfonate.

R₃, R₄, R₅, R₆, R₁₀, R₁₁, R₁₂, R₁₃, R₁₅, R₁₆, R₁₇ and R₁₈ preferablyrepresent, independently of each other, a hydrogen atom; a linear orbranched C₁-C₄ alkyl radical, optionally substituted with one or moreradicals chosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy,amino, C₁-C₂ (di)alkylamino, carboxyl and sulfonic radicals; a phenylradical optionally substituted with one or more radicals chosen fromhydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂(di)alkylamino, carboxyl and sulfonic radicals or a halogen atom such aschlorine, fluorine or bromine; a carboxyl radical; a sulfonylaminoradical; a sulfonic radical; a C₁-C₂ alkoxy radical; a C₂-C₄(poly)hydroxyalkoxy radical; an amino radical; a C₁-C₂ (di)alkylaminoradical; a C₂-C₄ (poly)hydroxyalkylamino radical.

More preferably, R₃, R₄, R₅, R₆, R₁₀, R₁₁, R₁₂, R₁₃, R₁₅, R₁₆, R₁₇ andR₁₈ represent a hydrogen atom, a C₁-C₄ alkyl radical optionallysubstituted with one or more radicals chosen from hydroxyl, amino andC₁-C₂ (di)alkylamino radicals; a carboxyl radical; a C₁-C₂ alkoxyradical; an amino radical; a C₁-C₂ (di)alkylamino radical; a C₂-C₄(poly)hydroxyalkylamino radical.

According to one particularly preferred embodiment, R₃, R₄, R₅, R₆, R₁₀,R₁₁, R₁₂, R₁₃, R₁₅, R₁₆, R₁₇ and R₁₈ represent a hydrogen atom, amethyl, phenyl or 2-hydroxymethyl radical, a carboxyl, a methoxy, ethoxyor 2-hydroxyethyloxy radical, or an amino, methylamino, dimethylamino or2-hydroxyethylamino radical.

R₇ and R₉ represent, independently of each other, a hydrogen atom; alinear or branched C₁-C₄ alkyl radical optionally substituted with oneor more radicals chosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄(poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl and sulfonicradicals; an optionally substituted phenyl radical; a carboxyl radical;a sulfonylamino radical.

Among these substituents, R₇ and R₉ preferably represent a hydrogenatom, a phenyl radical or a C₁-C₄ alkyl radical optionally substitutedwith one or more radicals chosen from hydroxyl, amino, C₁-C₂(di)alkylamino and carboxyl radicals.

According to one particularly preferred embodiment, R₇ and R₉ preferablyrepresent a hydrogen atom, a methyl, phenyl or 2-hydroxymethyl radicalor a carboxyl.

R₁₄ preferably represents a hydrogen atom; a linear or branched C₁-C₆alkyl radical, optionally substituted with one or more radicals chosenfrom hydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂(di)alkylamino, carboxyl and sulfonic radicals; an optionallysubstituted phenyl radical.

R₁₄ preferably represents a hydrogen atom; a linear or branched C₁-C₄alkyl radical, optionally substituted with one or more radicals chosenfrom hydroxyl, C₁-C₂ alkoxy, amino and C₁-C₂ (di)alkylamino radicals.

R₁₄ preferably represents a hydrogen atom; a methyl, ethyl,2-hydroxyethyl, 2-aminoethyl, 2-methoxyethyl, 1-carboxymethyl,2-carboxyethyl or 2-sulfonylethyl radical.

R₁₄ preferably represents a hydrogen atom; a methyl, ethyl,2-hydroxyethyl or 2-aminoethyl radical.

R₁, R₂ and R₈ represent a linear or branched C₁-C₈ alkyl radical,optionally substituted with one or more radicals chosen from hydroxyl,C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino,carboxyl and sulfonic radicals; an optionally substituted phenylradical.

Among these substituents, R₁, R₂ and R₈ preferably represent a C₁-C₄alkyl radical optionally substituted with one or more radicals chosenfrom hydroxyl, C₁-C₂ alkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl andsulfonic radicals.

According to one particularly preferred embodiment, R₁, R₂ and R₈preferably represent a methyl, ethyl, 2-hydroxyethyl, 1-carboxymethyl,2-carboxyethyl or 2-sulfonylethyl radical.

W₁ preferably represents a triazolium, thiazolium or pyridinium cationicgroup substituted with the preferred radicals R₁, R₂, R₇, R₁₀, R₁₁, R₁₂and R₁₃.

W₂ preferably represents a phenyl or pyridyl group substituted with thepreferred radicals R₃, R₄, R₅ and R₆.

W₃ and W₅ preferably represent, independently of each other, a group—NR₁₄—, with the preferred meanings of R₁₄.

W₄ preferably represents a linear or branched C₂-C₆ alkyl radical,optionally substituted with one or more radicals chosen from hydroxyl,C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino,carboxyl and sulfonic radicals; a phenyl radical optionally substitutedwith one or more radicals chosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄(poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl and sulfonicradicals or a halogen atom such as chlorine, fluorine or bromine; anaphthyl radical optionally substituted with one or more radicals chosenfrom hydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂(di)alkylamino, carboxyl and sulfonic radicals or a halogen atom such aschlorine, fluorine or bromine, or a piperazine radical formed with thetwo radicals W₃ and W₅.

W₄ preferably represents a linear or branched C₂-C₄ alkyl radical,optionally substituted with one or more hydroxyl radicals; a phenylradical optionally substituted with one or more radicals chosen fromhydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂(di)alkylamino, carboxyl and sulfonic radicals; a naphthyl radicaloptionally substituted with one or more radicals chosen from hydroxyl,C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino,carboxyl and sulfonic radicals, or a piperazine radical formed with thetwo radicals W₃ and W₅.

W₄ preferably represents an ethyl, propyl, butyl or 2-hydroxypropylradical; a phenyl radical; a naphthyl radical; a piperazine ring formedwith the two radicals W₃ and W₅.

L preferably represents a group chosen from —CO—; —CO—CH₂—CH₂—CO—;—CO—CO—; benzo-1,4-dicarbonyl; ethyl; 1,4-phenyl; triazine; pyrimidine.

L preferably represents an ethyl or triazine group.

The concentration of dicationic diazo dye of formula (I) may range from0.001% to 5% by weight approximately, and preferably from about 0.05% to2% by weight, relative to the total weight of the dye composition.

Among the dicationic diazo dyes of formula (I) according to the presentinvention, mention may be made especially of the compounds having thefollowing formulae:

Among these compounds, the ones even more particularly preferredaccording to the invention are those comprising a triazolium ring.

In the above formulae, Me denotes a CH₃ radical.

The dye composition in accordance with the invention may also containdirect dyes other than those of formula (I), these dyes possibly beingchosen especially from neutral, acidic or cationic nitrobenzene directdyes, neutral, acidic or cationic azo direct dyes, quinone and inparticular neutral, acidic or cationic anthraquinone direct dyes, azinedirect dyes, methine direct dyes, triarylmethane direct dyes, indoaminedirect dyes and natural direct dyes.

Among the benzenic direct dyes that may be used according to theinvention, mention may be made, in a non-limiting manner, of thefollowing compounds:

-   -   1,4-diamino-2-nitrobenzene    -   1-amino-2-nitro-4-(β-hydroxyethylamino)benzene    -   1-amino-2-nitro-4-bis(β-hydroxyethyl)aminobenzene    -   1,4-bis(β-hydroxyethylamino)-2-nitrobenzene    -   1-β-hydroxyethylamino-2-nitro-4-bis-(β-hydroxyethylamino)benzene    -   1-β-hydroxyethylamino-2-nitro-4-aminobenzene    -   1-β-hydroxyethylamino-2-nitro-4-(ethyl)(β-hydroxyethyl)aminobenzene    -   1-amino-3-methyl-4-β-hydroxyethylamino-6-nitrobenzene    -   1-amino-2-nitro-4-β-hydroxyethylamino-5-chlorobenzene    -   1,2-diamino-4-nitrobenzene    -   1-amino-2-β-hydroxyethylamino-5-nitrobenzene    -   1,2-bis(β-hydroxyethylamino)-4-nitrobenzene    -   1-amino-2-[tris(hydroxymethyl)methylamino]-5-nitrobenzene    -   1-hydroxy-2-amino-5-nitrobenzene    -   1-hydroxy-2-amino-4-nitrobenzene    -   1-hydroxy-3-nitro-4-aminobenzene    -   1-hydroxy-2-amino-4,6-dinitrobenzene    -   1-β-hydroxyethyloxy-2-β-hydroxyethylamino-5-nitrobenzene    -   1-methoxy-2-β-hydroxyethylamino-5-nitrobenzene    -   1-β-hydroxyethyloxy-3-methylamino-4-nitrobenzene    -   1-β,γ-dihydroxypropyloxy-3-methylamino-4-nitrobenzene    -   1-β-hydroxyethylamino-4-β,γ-dihydroxypropyloxy-2-nitrobenzene    -   1-β,γ-dihydroxypropylamino-4-trifluoromethyl-2-nitrobenzene    -   1-β-hydroxyethylamino-4-trifluoromethyl-2-nitrobenzene    -   1-β-hydroxyethylamino-3-methyl-2-nitrobenzene    -   1-β-aminoethylamino-5-methoxy-2-nitrobenzene    -   1-hydroxy-2-chloro-6-ethylamino-4-nitrobenzene    -   1-hydroxy-2-chloro-6-amino-4-nitrobenzene    -   1-hydroxy-6-[bis(β-hydroxyethyl)amino]-3-nitrobenzene    -   1-β-hydroxyethylamino-2-nitrobenzene    -   1-hydroxy-4-β-hydroxyethylamino-3-nitrobenzene.

Among the azo direct dyes that may be used according to the invention,mention may be made of the cationic azo dyes described in patentapplications WO 95/15144, WO 95/01772 and EP 714 954, the content ofwhich forms an integral part of the invention.

Among these compounds, mention may be made most particularly of thefollowing dyes:

-   -   1,3-dimethyl-2-[[4-(dimethylamino)phenyl]azo]-1H-imidazolium        chloride,    -   1,3-dimethyl-2-[(4-aminophenyl)azo]-1H-imidazolium chloride,    -   1-methyl-4-[(methylphenylhydrazono)methyl]pyridinium methyl        sulfate.

Among the azo direct dyes that may also be mentioned are the followingdyes described in the Colour Index International 3rd edition:

-   -   Disperse Red 17    -   Acid Yellow 9    -   Acid Black 1    -   Basic Red 22    -   Basic Red 76    -   Basic Yellow 57    -   Basic Brown 16    -   Acid Yellow 36    -   Acid Orange 7    -   Acid Red 33    -   Acid Red 35    -   Basic Brown 17    -   Acid Yellow 23    -   Acid Orange 24    -   Disperse Black 9.

Mention may also be made of1-(4′-aminodiphenylazo)-2-methyl-4-[bis(β-hydroxyethyl)amino]benzene and4-hydroxy-3-(2-methoxyphenylazo)-1-naphthalenesulfonic acid.

Among the quinone direct dyes that may be mentioned are the followingdyes:

-   -   Disperse Red 15    -   Solvent Violet 13    -   Acid Violet 43    -   Disperse Violet 1    -   Disperse Violet 4    -   Disperse Blue 1    -   Disperse Violet 8    -   Disperse Blue 3    -   Disperse Red 11    -   Acid Blue 62    -   Disperse Blue 7    -   Basic Blue 22    -   Disperse Violet 15    -   Basic Blue 99        and also the following compounds:    -   1-N-methylmorpholiniumpropylamino-4-hydroxyanthraquinone    -   1-aminopropylamino-4-methylaminoanthraquinone    -   1-aminopropylaminoanthraquinone    -   5-β-hydroxyethyl-1,4-diaminoanthraquinone    -   2-aminoethylaminoanthraquinone    -   1,4-bis(β,γ-dihydroxypropylamino)anthraquinone

Among the azine dyes that may be mentioned are the following compounds:

-   -   Basic Blue 17    -   Basic Red 2.

Among the triarylmethane dyes that may be used according to theinvention, mention may be made of the following compounds:

-   -   Basic Green 1    -   Acid Blue 9    -   Basic Violet 3    -   Basic Violet 14    -   Basic Blue 7    -   Acid Violet 49    -   Basic Blue 26    -   Acid Blue 7

Among the indoamine dyes that may be used according to the invention,mention may be made of the following compounds:

-   -   2-β-hydroxyethylamino-5-[bis(β-4′-hydroxyethyl)amino]-anilino-1,4-benzoquinone;    -   2-β-hydroxyethylamino-5-(2′-methoxy-4′-amino)anilino-1,4-benzoquinone;    -   3-N(2′-chloro-4′-hydroxy)phenylacetylamino-6-methoxy-1,4-benzoquinoneimine;    -   3-N(3′-chloro-4′-methylamino)phenylureido-6-methyl-1,4-benzoquinoneimine;    -   3-[4′-N-(ethylcarbamylmethyl)amino]phenylureido-6-methyl-1,4-benzoquinoneimine.

Among the natural direct dyes that may be used according to theinvention, mention may be made of lawsone, juglone, alizarin, purpurin,carminic acid, kermesic acid, purpurogallin, protocatechaldehyde,indigo, isatin, curcumin, spinulosin and apigenidin. Extracts ordecoctions containing these natural dyes may also be used, andespecially henna-based poultices or extracts.

The additional direct dye(s) preferably represent(s) from 0.001% to 20%by weight approximately, and even more preferably from 0.005% to 10% byweight approximately, relative to the total weight of the product.

The composition of the invention may also comprise an oxidizing agent.This oxidizing agent may be any oxidizing agent conventionally used forbleaching keratin fibers. The oxidizing agent is preferably chosen fromhydrogen peroxide, urea peroxide, alkali metal bromates, persalts suchas perborates and persulfates, peracids and enzymes, among which mentionmay be made of peroxidases, 2-electron oxidoreductases such as uricases,and 4-electron oxigenases such as laccases. The use of hydrogen peroxideis particularly preferred.

The composition according to the invention may also comprise anoxidation base. This oxidation base may be chosen from the oxidationbases conventionally used in oxidation dyeing, for examplepara-phenylenediamines, bis(phenyl)alkylenediamines, para-aminophenols,ortho-aminophenols and heterocyclic bases.

Among the para-phenylenediamines that may be mentioned, for example, arepara-phenylenediamine, para-tolylenediamine,2-chloro-para-phenylenediamine, 2,3-dimethyl-para-phenylenediamine,2,6-dimethyl-para-phenylene-diamine, 2,6-diethyl-para-phenylenediamine,2,5-dimethyl-para-phenylenediamine, N,N-dimethyl-para-phenylenediamine,N,N-diethyl-para-phenylenediamine, N,N-dipropyl-para-phenylenediamine,4-amino-N,N-diethyl-3-methylaniline,N,N-bis(β-hydroxyethyl)-para-phenylenediamine,4-N,N-bis(β-hydroxyethyl)amino-2-methylaniline,4-N,N-bis(β-hydroxyethyl)amino-2-chloroaniline,2-β-hydroxyethyl-para-phenylenediamine, 2-fluoro-para-phenylenediamine,2-isopropyl-para-phenylenediamine,N-(β-hydroxypropyl)-para-phenylenediamine,2-hydroxymethyl-para-phenylenediamine,N,N-dimethyl-3-methyl-para-phenylenediamine,N-ethyl-N-(β-hydroxyethyl)-para-phenylenediamine,N-(β,γ-dihydroxypropyl)-para-phenylenediamine,N-(4′-aminophenyl)-para-phenylenediamine,N-phenyl-para-phenylenediamine,2-β-hydroxyethyloxy-para-phenylenediamine,2-β-acetylamino-ethyloxy-para-phenylenediamine,N-(β-methoxyethyl)-para-phenylenediamine, 4-aminophenylpyrrolidine,2-thienyl-para-phenylenediamine, 2-β-hydroxyethylamino-5-aminotoluene,and the addition salts thereof with an acid.

Among the para-phenylenediamines mentioned above, para-phenylenediamine,para-tolylenediamine, 2-isopropyl-para-phenylenediamine,2-β-hydroxyethyl-para-phenylene-diamine,2-β-hydroxyethyloxy-para-phenylenediamine,2,6-dimethyl-para-phenylenediamine, 2,6-diethyl-para-phenylenediamine,2,3-dimethyl-para-phenylenediamine,N,N-bis(β-hydroxyethyl)-para-phenylenediamine,2-chloro-para-phenylenediamine and2-β-acetylaminoethyloxy-para-phenylenediamine, and the addition saltsthereof with an acid, are particularly preferred.

Among the bis(phenyl)alkylenediamines that may be mentioned, forexample, areN,N′-bis(β-hydroxyethyl)-N,N′-bis(4′-aminophenyl)-1,3-diaminopropanol,N,N′-bis(β-hydroxyethyl)-N,N′-bis(4′-aminophenyl)ethylenediamine,N,N′-bis(4-aminophenyl)-tetramethylenediamine,N,N′-bis(β-hydroxyethyl)-N,N′-bis(4-aminophenyl)tetramethylenediamine,N,N′-bis(4-methylamino-phenyl)tetramethylenediamine,N,N′-bis(ethyl)-N,N′-bis(4′-amino-3′-methylphenyl)ethylenediamine and1,8-bis (2,5-diaminophenoxy)-3,6-dioxaoctane, and the addition saltsthereof with an acid.

Among the para-aminophenols that may be mentioned, for example, arepara-aminophenol, 4-amino-3-methylphenol, 4-amino-3-fluorophenol,4-amino-3-hydroxymethylphenol, 4-amino-2-methylphenol,4-amino-2-hydroxymethylphenol, 4-amino-2-methoxymethylphenol,4-amino-2-aminomethylphenol,4-amino-2-(β-hydroxyethyl-aminomethyl)phenol and 4-amino-2-fluorophenol,and the addition salts thereof with an acid.

Among the ortho-aminophenols that may be mentioned, for example, are2-aminophenol, 2-amino-5-methylphenol, 2-amino-6-methylphenol and5-acetamido-2-aminophenol, and the addition salts thereof with an acid.

Among the heterocyclic bases that may be mentioned, for example, arepyridine derivatives, pyrimidine derivatives and pyrazole derivatives.

Among the pyridine derivatives that may be mentioned are the compoundsdescribed, for example, in patents GB 1 026 978 and GB 1 153 196, suchas 2,5-diaminopyridine, 2-(4-methoxyphenyl)amino-3-aminopyridine,2,3-diamino-6-methoxypyridine,2-(β-methoxyethyl)amino-3-amino-6-methoxypyridine and3,4-diaminopyridine, and the addition salts thereof with an acid.

Among the pyrimidine derivatives that can be mentioned are the compoundsdescribed, for example, in patents DE 2 359 399; JP 88-169 571; JP05-163 124; EP 0 770 375 or patent application WO 96/15765, such as2,4,5,6-tetraaminopyrimidine, 4-hydroxy-2,5,6-triaminopyrimidine,2-hydroxy-4,5,6-triaminopyrimidine, 2,4-dihydroxy-5,6-diaminopyrimidineand 2,5,6-triaminopyrimidine, and pyrazolopyrimidine derivatives such asthose mentioned in patent application FR-A-2 750 048 and among whichmention may be made of pyrazolo[1,5-a]pyrimidine-3,7-diamine;2,5-dimethylpyrazolo[1,5-a]pyrimidine-3,7-diamine;pyrazolo[1,5-a]pyrimidine-3,5-diamine;2,7-dimethylpyrazolo[1,5-a]pyrimidine-3,5-diamine;3-aminopyrazolo[1,5-a]pyrimidin-7-ol;3-aminopyrazolo[1,5-a]pyrimidin-5-ol;2-(3-aminopyrazolo[1,5-a]pyrimidin-7-ylamino)ethanol,2-(7-aminopyrazolo[1,5-a]pyrimidin-3-ylamino)ethanol,2-[(3-aminopyrazolo[1,5-a]pyrimidin-7-yl) (2-hydroxyethyl)amino]ethanol,2-[(7-aminopyrazolo[1,5-a]pyrimidin-3-yl)(2-hydroxyethyl)amino]ethanol,5,6-dimethylpyrazolo[1,5-a]-pyrimidine-3,7-diamine,2,6-dimethylpyrazolo-[1,5-a]pyrimidine-3,7-diamine,2,5,N7,N7-tetramethyl-pyrazolo[1,5-a]pyrimidine-3,7-diamine and3-amino-5-methyl-7-imidazolylpropylaminopyrazolo[1,5-a]pyrimidine, andthe addition salts thereof with an acid and the tautomeric formsthereof, when a tautomeric equilibrium exists.

Among the pyrazole derivatives that may be mentioned are the compoundsdescribed in patents DE 3 843 892 and DE 4 133 957 and patentapplications WO 94/08969, WO 94/08970, FR-A-2 733 749 and DE 195 43 988,such as 4,5-diamino-1-methylpyrazole,4,5-diamino-1-(β-hydroxyethyl)pyrazole, 3,4-diaminopyrazole,4,5-diamino-1-(4′-chlorobenzyl)pyrazole,4,5-diamino-1,3-dimethylpyrazole, 4,5-diamino-3-methyl-1-phenylpyrazole,4,5-diamino-1-methyl-3-phenylpyrazole,4-amino-1,3-dimethyl-5-hydrazinopyrazole,1-benzyl-4,5-diamino-3-methylpyrazole,4,5-diamino-3-tert-butyl-1-methylpyrazole,4,5-diamino-1-tert-butyl-3-methylpyrazole,4,5-diamino-1-(β-hydroxyethyl)-3-methylpyrazole,4,5-diamino-1-ethyl-3-methylpyrazole,4,5-diamino-1-ethyl-3-(4′-methoxyphenyl)pyrazole,4,5-diamino-1-ethyl-3-hydroxymethylpyrazole,4,5-diamino-3-hydroxymethyl-1-methylpyrazole,4,5-diamino-3-hydroxymethyl-1-isopropylpyrazole,4,5-diamino-3-methyl-1-isopropylpyrazole,4-amino-5-(2′-aminoethyl)amino-1,3-dimethylpyrazole,3,4,5-triaminopyrazole, 1-methyl-3,4,5-triaminopyrazole,3,5-diamino-1-methyl-4-methylaminopyrazole and3,5-diamino-4-(β-hydroxyethyl)amino-1-methylpyrazole, and the additionsalts thereof with an acid.

The composition according to the invention may also contain one or morecouplers conventionally used for dyeing keratin fibers. Among thesecouplers, mention may be made especially of meta-phenylenediamines,meta-aminophenols, meta-diphenols, naphthalene-based couplers andheterocyclic couplers.

Examples that may be mentioned include 2-methyl-5-aminophenol,5-N-(β-hydroxyethyl)amino-2-methylphenol,6-chloro-2-methyl-5-aminophenol, 3-aminophenol, 1,3-dihydroxybenzene,1,3-dihydroxy-2-methylbenzene, 4-chloro-1,3-dihydroxybenzene,2,4-diamino-1-(β-hydroxyethyloxy)benzene,2-amino-4-(β-hydroxyethylamino)-1-methoxybenzene, 1,3-diaminobenzene,1,3-bis(2,4-diaminophenoxy)propane, 3-ureidoaniline,3-ureido-1-dimethylaminobenzene, sesamol,1-β-hydroxyethylamino-3,4-methylenedioxybenzene, α-naphthol,2-methyl-1-naphthol, 6-hydroxyindole, 4-hydroxyindole,4-hydroxy-N-methylindole, 2-amino-3-hydroxypyridine,6-hydroxybenzomorpholine, 3,5-diamino-2,6-dimethoxypyridine,1-N-(β-hydroxyethyl)amino-3,4-methylenedioxybenzene and2,6-bis(β-hydroxy-ethylamino)toluene and the addition salts thereof withan acid.

In the composition of the present invention, the coupler(s) is(are)generally present in an amount ranging from 0.001% to 10% by weightapproximately, and more preferably from 0.005% to 6% by weight, relativeto the total weight of the dye composition. The oxidation base(s)is(are) present in an amount preferably ranging from 0.001% to 10% byweight approximately, and more preferably from 0.005% to 6% by weight,relative to the total weight of the dye composition.

In general, the addition salts with an acid that may be used in thecontext of the dye compositions of the invention for the oxidation basesand couplers are chosen especially from the hydrochlorides,hydrobromides, sulfates, citrates, succinates, tartrates, lactates,tosylates, benzenesulfonates, phosphates and acetates.

The medium that is suitable for dyeing, also known as the dye support,generally consists of water or a mixture of water and at least oneorganic solvent to dissolve the compounds which would not besufficiently soluble in water. As organic solvent, mention may be made,for example, of C₁-C₄ lower alkanols, such as ethanol and isopropanol;polyols and polyol ethers such as 2-butoxyethanol, propylene glycol,propylene glycol monomethyl ether, diethylene glycol monoethyl ether andmonomethyl ether, as well as aromatic alcohols such as benzyl alcohol orphenoxyethanol, and mixtures thereof.

The organic solvents may preferably be present in proportions of between1% and 40% by weight approximately relative to the total weight of thedye composition, and even more preferably between 5% and 30% by weightapproximately.

The dye composition in accordance with the invention can also containvarious adjuvants conventionally used in compositions for dyeing thehair, such as anionic, cationic, nonionic, amphoteric or zwitterionicsurfactants or mixtures thereof, anionic, cationic, nonionic, amphotericor zwitterionic polymers or mixtures thereof, inorganic or organicthickeners, and in particular anionic, cationic, nonionic or amphotericassociative polymeric thickeners, antioxidants, penetration agents,sequestering agents, fragrances, buffers, dispersing agents, packagingagents such as, for example, silicones, which may or may not be volatileor modified, film-forming agents, ceramides, preserving agents andopacifiers.

The above adjuvants are generally present in an amount for each of themof between 0.01% and 20% by weight relative to the weight of thecomposition.

Needless to say, a person skilled in the art will take care to selectthis or these optional additional compounds such that the advantageousproperties intrinsically associated with the oxidation dye compositionin accordance with the invention are not, or are not substantially,adversely affected by the addition(s) envisaged.

The pH of the dye composition in accordance with the invention isgenerally between about 3 and 12 and preferably between about 5 and 11.It may be adjusted to the desired value using acidifying or basifyingagents usually used in the dyeing of keratin fibers, or alternativelyusing standard buffer systems.

Among the acidifying agents which may be mentioned, for example, areinorganic or organic acids such as hydrochloric acid, orthophosphoricacid, sulfuric acid, carboxylic acids such as acetic acid, tartaricacid, citric acid and lactic acid, and sulfonic acids.

Among the basifying agents which may be mentioned, for example, areaqueous ammonia, alkaline carbonates, alkanolamines such as mono-, di-and triethanolamine and derivatives thereof, sodium hydroxide, potassiumhydroxide and the compounds of formula (III) below:

in which W is a propylene residue which is unsubstituted or substitutedwith a hydroxyl group or a C₁-C₄ alkyl radical; R₆, R₇, R₈ and R₉, whichmay be identical or different, represent a hydrogen atom, a C₁-C₄ alkylradical or a C₁-C₄ hydroxyalkyl radical.

The dye composition according to the invention may be in various forms,such as in the form of liquids, creams or gels, or in any other formthat is suitable for dyeing keratin fibers, and especially human hair.

A subject of the invention is also a process of direct dyeing, whichcomprises the application of a dye composition comprising a dye offormula (I) as defined above to keratin fibers. After a leave-in time,the keratin fibers are rinsed, revealing colored fibers.

The dye composition comprising the cationic azo dye of formula (I) maybe applied to the fibers in the presence of an oxidizing agent, whichcauses bleaching of the fiber (lightening direct dyeing). This oxidizingagent may be added to the composition comprising the cationic azo dye atthe time of use or directly onto the keratin fiber.

A subject of the invention is also a process of oxidation dyeing, whichcomprises the application to the fibers of a dye composition comprisinga dye of formula (I), at least one oxidation base and optionally atleast one coupler, in the presence of an oxidizing agent.

The oxidation base, the coupler and the oxidizing agent are as definedabove.

The color may be revealed at acidic, neutral or alkaline pH and theoxidizing agent may be added to the composition of the invention just atthe time of use, or it may be introduced using an oxidizing compositioncontaining it, applied to the fibers simultaneously with or sequentiallyto the dye composition.

In the case of oxidation dyeing or lightening direct dyeing, the dyecomposition is mixed, preferably at the time of use, with a compositioncontaining, in a medium that is suitable for dyeing, at least oneoxidizing agent, this oxidizing agent being present in an amount that issufficient to develop a coloration. The mixture obtained is then appliedto the keratin fibers. After a leave-in time of 3 to 50 minutesapproximately and preferably 5 to 30 minutes approximately, the keratinfibers are rinsed, washed with shampoo, rinsed again and then dried.

The oxidizing composition may also contain various adjuvantsconventionally used in compositions for dyeing the hair, and as definedabove.

The pH of the oxidizing composition containing the oxidizing agent issuch that, after mixing with the dye composition, the pH of theresulting composition applied to the keratin fibers preferably rangesfrom 3 to 12 approximately, and even more preferably between 5 and 11.It may be adjusted to the desired value by means of acidifying orbasifying agents usually used in the dyeing of keratin fibers, and asdefined above.

The composition that is finally applied to the keratin fibers may be invarious forms, such as in the form of liquids, creams or gels or in anyother form that is suitable for dyeing keratin fibers, and especiallyhuman hair.

Another subject of the invention is a multi-compartment device or dyeing“kit”, in which a first compartment contains the dye composition of theinvention and a second compartment contains the oxidizing composition.This device may be equipped with a means for applying the desiredmixture to the hair, such as the devices described in patent FR-2 586913 in the name of the Applicant.

Finally, a subject of the invention is also novel dicationic diazo dyesof formula (I) as defined above, for which,

-   -   when p=1,        -   W₁ to W₅ and L have the same meanings as defined above,    -   when p=0,        -   W₃ represents an oxygen atom and the other groups of            formula (I) have the same meanings as defined above, or        -   W₃ represents a radical —NR₁₄— and L represents an aryl or            heteroaryl radical optionally substituted with one or more            radicals chosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄            (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl            and sulfonic radicals, or a halogen atom such as chlorine,            fluorine or bromine.            Synthesis of the Compounds of the Invention

The methods for obtaining said compounds are based on reactions that arealready well known in the literature and disclosed, for example, in thefollowing documents: U.S. Pat. No. 3,291,788, GB-1 186 753, U.S. Pat.No. 3,271,383, EP-0 757 083 and U.S. Pat. No. 5,708,151.

A first synthetic principle consists in starting with a 5- or 6-memberedamino heterocycle, such as 3-aminotriazole, 2-aminothiazole,3-aminothiadiazole, 2-aminopyridine or 2-aminopyridazine, which isreacted with sodium nitrite in a polar acidic protic solvent, such asacetic acid or hydrochloric acid, at a temperature generally of between−10° C. and 50° C., in order to generate the corresponding diazoniumsalt. This salt then reacts with an aromatic derivative of formula (A)or (B) described below, in which:

W₃, W₅, X₁, X₂ and L have the meanings described above according to theinvention. These aromatic derivatives are obtained by applying theconventional SNAr (aromatic nucleophilic substitution), SN1(nucleophilic substitution 1) and SN2 (nucleophilic substitution 2)reactions of the literature.

The resulting condensation product then reacts with an alkylating agentsuch as a dialkyl sulfate or an alkyl halide in a polar solvent and at atemperature of between 0° C. and 150° C. and preferably between 20° C.and 100° C. The 5- or 6-membered heterocyclic part is thus quaternizedand the azo compound obtained is cationic.

With a 5-membered heterocycle:

With a 6-membered heterocycle:

-   -   A second synthetic principle consists in reacting a heterocyclic        azo compound 1 quaternized on one of the nitrogen atoms of the        heterocycle as a 4-methoxyphenylazo series, with an aniline or        phenol derivative or a heteroaromatic amine 2 in a protic        solvent at a temperature of between 25° C. and 150° C. In        particular, the quaternary heterocycle may be a triazolium,        thiazolium, thiadiazolium or oxazolium. The same synthetic        principle may be applied in the 6-membered heterocyclic series,        such as pyridinium or pyridazinium, giving the compounds of        formula 4′ from the azo compound 1′.

The cationic azo derivative 3 then reacts with a di-electrophile such asan alkyl dihalide, an alkylaryl dihalide, a triazine dihalide, apyrimidine dihalide or a diacyl chloride, to give the cationic azocompound 4.

In the particular case in which W₅ represents an amino, the derivative 3may react with an aryl dihalide in the presence of a transition metalsuch as palladium (II) or copper (I) to give compound 4 according to theBuchwald or Meerwein reaction, which are well known in the literature.

-   -   A third synthetic principle consists in reacting a heterocyclic        azo compound 1 quaternized on one of the nitrogen atoms of the        heterocycle as a 4-methoxyphenylazo series, with a diamino        derivative of the type W₃-L-W₃ (in which W₃═NH₂) in a protic        solvent at a temperature of between 25° C. and 150° C. In        particular, the quaternary heterocycle may be a triazolium,        thiazolium, thiadiazolium or oxazolium. The compounds of formula        5 are thus obtained. The same synthetic principle may be applied        in the 6-membered heterocyclic series, such as pyridinium or        pyridazinium, to give the compounds of formula 5′ from the azo        compound 1′.

In the formulae of the synthetic scheme, Me denotes a CH₃ radical.

EXAMPLE OF SYNTHESIS

Compound b having the formula below in accordance with the invention isobtained according to process 1 or process 2 below (in which Me denotesa CH₃ radical)

Process 1:

Process 2:

The diazonium salt of 3-aminotriazole (0.5 mmol) is prepared accordingto the protocol described in patent GB-1 186 753 or U.S. Pat. No.3,291,788. A solution of 1 mmol of bis(N-phenylamino)propane in 10 ml of15% sulfuric acid is added at 0° C. to the diazonium salt prepared abovewith vigorous stirring. After disappearance of the reagents, thereaction medium is poured onto ice and the precipitate is filtered offby suction, washed with water and then dried to constant weight to givecompound d.

Compound d (0.2 mmol) is then dissolved in 30 ml of dimethylformamideand 1 mmol of dimethyl sulfate is added to this solution. The reactionmedium is then brought to 90-100° C. with stirring. After 6 hours, thereaction medium is poured into 100 ml of water at room temperature andthe solution is concentrated to dryness to constant weight to give 0.04mmol of the desired compound b, the λ_(max) of which is 520 nm in amethanolic 1% acetic acid solution.

The dye obtained dyed hair in an iridescent red shade.

1. A method of dyeing human keratin fibers, comprising applying to thekeratin fibers a composition comprising: a cosmetic medium suitable fordyeing human keratin fibers, wherein said medium is water or a mixtureof water and at least one organic solvent suitable for dyeing humankeratin fibers, and at least one dicationic diazo dye of formula (I),comprised in said medium:[W₁—N═N—W₂—W₃—(W₄—W₅)_(p)-]₂-L  Formula (I) wherein: p=0 or 1, W₁ ischosen from heteroaromatic radicals of formulae (II) and (III):

W₂ is chosen from carbon-based, pyridine-based and pyridazine-basedaromatic groups of formula (IV):

W₃ and W₅, which may be identical or different, are chosen from —NR₁₄—radicals, and oxygen and nitrogen atoms, W₄ is chosen from saturated andunsaturated, linear and branched C₁-C₁₆ hydrocarbon-based chains, whichcan form at least one 3- to 6-membered carbon-based ring, wherein atleast one carbon atom of the carbon-based chain may optionally bereplaced with an entity chosen from oxygen, nitrogen and sulfur atomsand from SO₂ groups, and further wherein the carbon atoms may optionallybe substituted, independently of each other, with at least one halogenatom, provided that W₄ does not comprise a peroxide bond or diazo ornitroso radicals; piperazine rings; and groups of formula (V):

wherein in formulae (II), (III), (IV) and (V): X₁ is chosen fromnitrogen atoms and CR₅ radicals, X₂ is chosen from nitrogen atoms andCR₆ radicals, X₃ is chosen from nitrogen atoms and CR₁₇ radicals, X₄ ischosen from nitrogen atoms and CR₁₈ radicals, Z₁ is chosen from oxygenand sulfur atoms, and NR₈ radicals, Z₂ is chosen from nitrogen atoms andCR₉ atoms, with the proviso that when Z₁ is chosen from NR₈ radicals, Z₂is not chosen from CR₉ radicals, such that formula (II) is not animidazolium ring, Z₃ is chosen from nitrogen atoms and CR₁₂ radicals, Z₄is chosen from nitrogen atoms and CR₁₃ radicals, the bond a of the5-membered cationic ring of formula (II) is linked to the azo group offormula (I), the bond b of the 6-membered cationic ring of formula (III)is linked to the azo group of formula (I), wherein when p=0, then L ischosen from linear and branched C₁-C₁₆ hydrocarbon-based chains, whichcan form at least one 3- to 6-membered carbon-based ring, wherein atleast one carbon atom of the carbon-based chain is optionally replacedwith an entity chosen from oxygen, nitrogen and sulfur atoms and fromSO₂ groups, and further wherein the carbon atoms of the chain areoptionally substituted, independently of each other, with at least onehalogen atom; with the proviso that L does not comprise a peroxide bondor diazo or nitroso radicals, wherein when p=1, then L is chosen fromsaturated and unsaturated, linear and branched C₁-C₁₆ hydrocarbon-basedchains, which can form at least one 3 to 6 membered carbon-based ring,wherein at least one carbon atom of the carbon-based chain is optionallyreplaced with an entity chosen from oxygen, nitrogen and sulfur atomsand from SO₂ groups; with the proviso that L does not comprise aperoxide bond or diazo or nitroso radicals, R₃, R₄, R₅, R₆, R₇, R₉, R₁₀,R₁₁, R₁₂, R₁₃, R₁₄, R₁₅, R₁₆, R₁₇ and R₁₈ which may be identical ordifferent, are chosen from hydrogen atoms, saturated and unsaturated,linear and branched C₁-C₁₆ hydrocarbon-based chains, which can form atleast one 3- to 6-membered carbon-based ring, wherein at least onecarbon atom of the carbon-based chain is optionally replaced with anentity chosen from oxygen, nitrogen and sulfur atoms, and from SO₂groups, and the carbon atoms of the chain are optionally substituted,independently of each other, with at least one halogen atom; and withthe proviso that R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂, R₁₃, R₁₄, R₁₅,R₁₆, R₁₇ and R₁₈ do not comprise a peroxide bond or diazo or nitrosoradicals, R₃ with R₄, R₇ with R₉, R₁₀ with R₁₁, R₁₂ with R₁₃ and R₁₅with R₁₆ may optionally form a carbon-based aromatic ring, R₁, R₂ and R₈are chosen from linear and branched C₁-C₈ alkyl radicals optionallysubstituted with at least one radical chosen from hydroxyl, C₁-C₂alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyland sulfonic radicals; and optionally substituted phenyl radicals, and Xis chosen from organic and mineral anions.
 2. The method according toclaim 1, wherein the human keratin fibers are hair.
 3. The methodaccording to claim 1, wherein R₃, R₄, R₅, R₆, R₁₀, R₁₁, R₁₂, R₁₃, R₁₅,R₁₆, R₁₇ and R₁₈, which may be identical or different, are chosen fromhydrogen atoms; linear and branched C₁-C₄ alkyl radicals, optionallysubstituted with at least one radical chosen from hydroxyl, C₁-C₂alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyland sulfonic radicals; phenyl radicals optionally substituted with atleast one radical chosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄(poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl and sulfonicradicals, and halogen atoms; carboxyl radicals; sulfonylamino radicals;sulfonic radicals; C₁-C₂ alkoxy radicals; C₂-C₄ (poly)hydroxyalkoxyradicals; amino radicals; C₁-C₂ (di)alkylamino radicals; and C₂-C₄(poly)hydroxyalkylamino radicals.
 4. The method according to claim 3,wherein R₃, R₄, R₅, R₆, R₁₀, R₁₁, R₁₂, R₁₃, R₁₅, R₁₆, R₁₇ and R₁₈ arechosen from hydrogen atoms; C₁-C₄ alkyl radicals optionally substitutedwith at least one radical chosen from hydroxyl, amino and C₁-C₂(di)alkylamino radicals; carboxyl radicals; C₁-C₂ alkoxy radicals; aminoradicals; C₁-C₂ (di)alkylamino radicals; and C₂-C₄(poly)hydroxyalkylamino radicals.
 5. The method according to claim 4,wherein R₃, R₄, R₅, R₆, R₁₀, R₁₁, R₁₂, R₁₃, R₁₅, R₁₆, R₁₇ and R₁₈ arechosen from hydrogen atoms; methyl, phenyl and 2-hydroxymethyl radicals;carboxyl, methoxy, ethoxy and 2-hydroxyethyloxy radicals; and amino,methylamino, dimethylamino and 2-hydroxyethylamino radicals.
 6. Themethod according to claim 1, wherein R₇ and R₉, which may be identicalor different, are chosen from hydrogen atoms; linear and branched C₁-C₄alkyl radicals optionally substituted with at least one radical chosenfrom hydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂(di)alkylamino, carboxyl and sulfonic radicals; optionally substitutedphenyl radicals; carboxyl radicals; and sulfonylamino radicals.
 7. Themethod according to claim 6, wherein R₇ and R₉ are chosen from hydrogenatoms; phenyl radicals and C₁-C₄ alkyl radicals optionally substitutedwith at least one radical chosen from hydroxyl, amino, C₁-C₂(di)alkylamino and carboxyl radicals.
 8. The method according to claim7, wherein R₇ and R₉ are chosen from hydrogen atoms; methyl, phenyl and2-hydroxymethyl radicals; and carboxyl radicals.
 9. The method accordingto claim 1, wherein R₁₄ is chosen from hydrogen atoms; linear andbranched C₁-C₆ alkyl radicals, optionally substituted with at least oneradical chosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy,amino, C₁-C₂ (di)alkylamino, carboxyl and sulfonic radicals; andoptionally substituted phenyl radicals.
 10. The method according toclaim 9, wherein R₁₄ is chosen from hydrogen atoms; linear and branchedC₁-C₄ alkyl radicals, optionally substituted with at least one radicalchosen from hydroxyl, C₁-C₂ alkoxy, amino and C₁-C₂ (di)alkylaminoradicals.
 11. The method according to claim 10, wherein R₁₄ is chosenfrom hydrogen atoms; methyl, ethyl, 2-hydroxyethyl, 2-aminoethyl,2-methoxyethyl, 1 -carboxymethyl, 2-carboxyethyl and 2-sulfonylethylradicals.
 12. The method according to claim 11, wherein R₁₄ is chosenfrom hydrogen atoms; methyl, ethyl, 2-hydroxyethyl and 2-aminoethylradicals.
 13. The method according to claim 1, wherein R₁, R₂ and R₈ arechosen from C₁-C₄ alkyl radicals optionally substituted with at leastone radical chosen from hydroxyl, C₁-C₂ alkoxy, amino, C₁-C₂(di)alkylamino, carboxyl and sulfonic radicals.
 14. The method accordingto claim 13, wherein R₁, and R₂ and R₈ are chosen from methyl, ethyl,2-hydroxyethyl, 1 -carboxymethyl, 2-carboxyethyl and 2-sulfonylethylradicals.
 15. The method according to claim 1, wherein W₁ is chosen fromtriazolium, thiazolium and pyridinium cationic groups of formulae (II)and (III), wherein R₁ and R₂ are chosen from linear and branched C₁-C₈alkyl radicals optionally substituted with at least one radical chosenfrom hydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂(di)alkylamino, carboxyl and sulfonic radicals; and optionallysubstituted phenyl radicals, R₇ is chosen from hydrogen atoms; linearand branched C₁-C₄ alkyl radicals optionally substituted with at leastone radical chosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄(poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl and sulfonicradicals; optionally substituted phenyl radicals; carboxyl radicals; andsulfonylamino radicals; and R₁₀, R₁₁, R₁₂ and R₁₃, which may beidentical or different, are chosen from hydrogen atoms; linear andbranched C₁-C₄ alkyl radicals, optionally substituted with at least oneradical chosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy,amino, C₁-C₂ (di)alkylamino, carboxyl and sulfonic radicals; phenylradicals optionally substituted with at least one radical chosen fromhydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂(di)alkylamino, carboxyl and sulfonic radicals, and halogen atoms;carboxyl radicals; sulfonylamino radicals; sulfonic radicals; C₁-C₂alkoxy radicals; C₂-C₄ (poly)hydroxyalkoxy radicals; amino radicals;C₁-C₂ (di)alkylamino radicals; and C₂-C₄ (poly)hydroxyalkylaminoradicals.
 16. The method according to claim 1, wherein W₂ is chosen fromphenyl and pyridyl groups of formula (IV), wherein R₃, R₄, R₅ and R₆,which may be identical or different, are chosen from hydrogen atoms;linear and branched C₁-C₄ alkyl radicals, optionally substituted with atleast one radical chosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄(poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl and sulfonicradicals; phenyl radicals optionally substituted with at least oneradical chosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy,amino, C₁-C₂ (di)alkylamino, carboxyl and sulfonic radicals, and halogenatoms; carboxyl radicals; sulfonylamino radicals; sulfonic radicals;C₁-C₂ alkoxy radicals; C₂-C₄ (poly)hydroxyalkoxy radicals; aminoradicals; C₁-C₂ (di)alkylamino radicals; and C₂-C₄(poly)hydroxyalkylamino radicals.
 17. The method according to claim 1,wherein W₃ and W₅, which may be identical or different, are chosen from—NR₁₄— groups, wherein R₁₄ is chosen from hydrogen atoms; linear andbranched C₁-C₆ alkyl radicals, optionally substituted with at least oneradical chosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy,amino, C₁-C₂ (di)alkylamino, carboxyl and sulfonic radicals; andoptionally substituted phenyl radicals.
 18. The method according toclaim 1, wherein W₄ is chosen from linear and branched C₂-C₆ alkylradicals optionally substituted with at least one radical chosen fromhydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂(di)alkylamino, carboxyl and sulfonic radicals; phenyl radicalsoptionally substituted with at least one radical chosen from hydroxyl,C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino,carboxyl and sulfonic radicals, and halogen atoms; naphthyl radicalsoptionally substituted with at least one radical chosen from hydroxyl,C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino,carboxyl and sulfonic radicals; halogen atoms; and piperazine radicalsformed with the two radicals W₃ and W₅.
 19. The method according toclaim 18, wherein W₄ is chosen from linear and branched C₂-C₄ alkylradicals optionally substituted with at least one hydroxyl radical;phenyl radicals optionally substituted with at least one radical chosenfrom hydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂(di)alkylamino, carboxyl and sulfonic radicals; naphthyl radicalsoptionally substituted with at least one radical chosen from hydroxyl,C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino,carboxyl and sulfonic radicals; and piperazine radicals formed with thetwo radicals W₃ and W₅.
 20. The method according to claim 19, wherein W₄is chosen from ethyl, propyl, butyl and 2-hydroxypropyl radicals; phenylradicals; naphthyl radicals; and piperazine rings formed with the tworadicals W₃ and W₅.
 21. The method according to claim 1, wherein L is anentity chosen from —CO—; —CO—CH₂—CH₂—CO—; —CO—CO—; benzo-1,4-dicarbonyl;ethyl; 1,4-phenyl; triazine; and pyrimidine.
 22. The method according toclaim 21, wherein L is chosen from ethyl and triazine groups.
 23. Themethod according to claim 1, wherein the at least one dicationic diazodye of formula (I) is present in an amount ranging from 0.001% to 5% byweight, relative to the total weight of the composition.
 24. The methodaccording to claim 23, wherein the at least one dicationic diazo dye offormula (I) is present in an amount ranging from 0.05% to 2% by weight,relative to the total weight of the composition.
 25. The methodaccording to claim 1 further comprising at least one oxidation base. 26.The method according to claim 25, wherein the at least one oxidationbase is chosen from para-phenylenediamines, bis(phenyl)alkylenediamines,para-aminophenols, ortho-aminophenols, heterocyclic bases, and the acidaddition salts thereof.
 27. The method according to claim 25, whereinthe at least one oxidation base is present in an amount ranging from0.001% to 10% by weight, relative to the total weight of thecomposition.
 28. The method according to claim 27, wherein the at leastone oxidation base is present in an amount ranging from 0.005% to 6% byweight, relative to the total weight of the composition.
 29. The methodaccording to claim 1, further comprising at least one coupler.
 30. Themethod according to claim 29, wherein the at least one coupler is chosenfrom meta-phenylenediamines, meta-aminophenols, meta-diphenols,naphthalene-based couplers, heterocyclic couplers, and the acid additionsalts thereof.
 31. The method according to claim 1 further comprising atleast one additional direct dye, chosen from neutral, acidic andcationic nitrobenzene direct dyes; neutral, acidic and cationic azodirect dyes; quinone direct dyes; azine direct dyes; methine directdyes; triarylmethane direct dyes; indoamine direct dyes; and naturaldirect dyes, with the proviso that the at least one additional directdye is other than those of formula (I).
 32. The method according toclaim 31, wherein the at least one quinone direct dye is chosen fromneutral, acidic and cationic anthraquinone direct dyes.
 33. The methodaccording to claim 1 further comprising at least one oxidizing agent.34. The method according to claim 33, wherein the at least one oxidizingagent is hydrogen peroxide.
 35. The method according to claim 1, whereinthe dye composition comprises at least one oxidizing agent.
 36. Themethod according to claim 35, wherein the at least one oxidizing agentis mixed with the dye composition at the time of use.
 37. The methodaccording to claim 35, wherein the at least one oxidizing agent isapplied to the fibers in the form of an oxidizing composition eithersimultaneously with, or sequentially to, the application of the dyecomposition.
 38. A process for the oxidation dyeing of human keratinfibers, comprising applying to the fibers, at least one dye compositionin the presence of at least one oxidizing agent, wherein the at leastone dye composition comprises at least one oxidation base, optionally atleast one coupler, and at least one dicationic diazo dye of formula (I):[W₁—N═N—W₂—W₃—(W₄—W₅)_(p)-]₂-L  Formula (I) wherein: p=0 or 1, W₁ ischosen from heteroaromatic radicals of formulae (II) and (III):

W₂ is chosen from carbon-based, pyridine-based and pyridazine-basedaromatic groups of formula (IV):

W₃ and W₅, which may be identical or different, are chosen from —NR₁₄—radicals, and oxygen and nitrogen atoms, W₄ is chosen from saturated andunsaturated, linear and branched C₁-C₁₆ hydrocarbon-based chains, whichcan form at least one 3- to 6-membered carbon-based ring, wherein atleast one carbon atom of the carbon-based chain may optionally bereplaced with an entity chosen from oxygen, nitrogen and sulfur atoms,and from SO₂ groups, and further wherein the carbon atoms may optionallybe substituted, independently of each other, with at least one halogenatom, provided that W₄ does not comprise a peroxide bond or diazo ornitroso radicals; piperazine rings; and groups of formula (V):

wherein in formulae (II), (III), (IV) and (V): X₁ is chosen fromnitrogen atoms and CR₅ radicals, X₂ is chosen from nitrogen atoms andCR₆ radicals, X₃ is chosen from nitrogen atoms and CR₁₇ radicals, X₄ ischosen from nitrogen atoms and CR₁₈ radicals, Z₁ is chosen from oxygenand sulfur atoms, and NR₈ radicals, Z₂ is chosen from nitrogen atoms andCR₉ atoms, with the proviso that when Z₁ is chosen from NR₈ radicals,then Z₂ is not chosen from CR₉ radicals, such that formula (II) is notan imidazolium ring, Z₃ is chosen from nitrogen atoms and CR₁₂ radicals,Z₄ is chosen from nitrogen atoms and CR₁₃ radicals, the bond a of the5-membered cationic ring of formula (II) is linked to the azo group offormula (I), the bond b of the 6-membered cationic ring of formula (III)is linked to the azo group of formula (I), wherein when p=0, then L ischosen from linear and branched C₁-C₁₆ hydrocarbon-based chains, whichcan form at least one 3- to 6-membered carbon-based ring, wherein atleast one carbon atom of the carbon-based chain is optionally replacedwith an entity chosen from oxygen, nitrogen and sulfur atoms, and fromSO₂ groups, and further wherein the carbon atoms of the chain areoptionally substituted, independently of each other, with at least onehalogen atom; with the proviso that L does not comprise a peroxide bondor diazo or nitroso radicals, wherein when p=1, then L is chosen fromsaturated and unsaturated, linear and branched C₁-C₁₆ hydrocarbon-basedchains, which can form at least one 3- to 6-membered carbon-based ring,wherein at least one carbon atom of the carbon-based chain is optionallyreplaced with an entity chosen from oxygen, nitrogen and sulfur atoms,and SO₂ groups; with the proviso that L does not comprise a peroxidebond or diazo or nitroso radicals, R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁,R₁₂, R₁₃, R₁₄, R₁₅, R₁₆, R₁₇ and R₁₈, which may be identical ordifferent, are chosen from hydrogen atoms, saturated and unsaturated,linear and branched C₁-C₁₆ hydrocarbon-based chains, which can form atleast one 3- to 6-membered carbon-based ring, wherein at least onecarbon atom of the carbon-based chain is optionally replaced with anentity chosen from oxygen, nitrogen and sulfur atoms, and from SO₂groups, and the carbon atoms of the chain are optionally substituted,independently of each other, with at least one halogen atom; and withthe proviso that R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂, R₁₃, R₁₄, R₁₅,R₁₆, R₁₇ and R₁₈ do not comprise a peroxide bond or diazo or nitrosoradicals, R₃ with R₄, R₇ with R₉, R₁₀ with R₁₁, R₁₂ with R₁₃ and R₁₅with R₁₆ can optionally form a carbon-based aromatic ring, R₁, R₂ and R₈are chosen from linear and branched C₁-C₈ alkyl radicals optionallysubstituted with at least one radical chosen from hydroxyl, C₁-C₂alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyland sulfonic radicals; and optionally substituted phenyl radicals, and Xis chosen from organic and mineral anions.
 39. The process according toclaim 38, wherein the human keratin fibers are hair.
 40. The processaccording to claim 38, wherein the at least one oxidizing agent is mixedwith the dye composition at the time of use.
 41. The process accordingto claim 38, wherein the at least one oxidizing agent is applied to thefibers in the form of an oxidizing composition either simultaneouslywith, or sequentially to, the application of the dye composition.
 42. Amulti-compartment kit, wherein at least one first compartment comprisesa composition comprising at least one dicationic diazo dye of formula(I):[W₁—N═N—W₂—W₃—(W₄—W₅)_(p)-]₂-L  Formula (I) wherein: p=0 or 1, W₁ ischosen from heteroaromatic radicals of formulae (II) and (III):

W₂ is chosen from carbon-based, pyridine-based and pyridazine-basedaromatic groups of formula (IV):

W₃ and W₅, which may be identical or different, are chosen from —NR₁₄—radicals, and oxygen and nitrogen atoms, W₄ is chosen from saturated andunsaturated, linear and branched C₁-C₁₆ hydrocarbon-based chains, whichcan form at least one 3- to 6-membered carbon-based ring, wherein atleast one carbon atom of the carbon-based chain may optionally bereplaced with an entity chosen from oxygen, nitrogen and sulfur atomsand from SO₂ groups, and further wherein the carbon atoms may optionallybe substituted, independently of each other, with at least one halogenatom, provided that W₄ does not comprise a peroxide bond or diazo ornitroso radicals; piperazine rings; and groups of formula (V):

wherein in formulae (II), (III), (IV) and (V): X₁ is chosen fromnitrogen atoms and CR₅ radicals, X₂ is chosen from nitrogen atoms andCR₆ radicals, X₃ is chosen from nitrogen atoms and CR₇ radicals, X₄ ischosen from nitrogen atoms and CR₁₈ radicals, Z₁ is chosen from oxygenand sulfur atoms, and NR₈ radicals, Z₂ is chosen from nitrogen atoms andCR₉ atoms, with the proviso that when Z₁ is chosen from NR₈ radicals,then Z₂ is not chosen from CR₉ radicals, such that formula (II) is notan imidazolium ring, Z₃ is chosen from nitrogen atoms and CR₁₂ radicals,Z₄ is chosen from nitrogen atoms and CR₁₃ radicals, the bond a of the5-membered cationic ring of formula (II) is linked to the azo group offormula (I), the bond b of the 6-membered cationic ring of formula (III)is linked to the azo group of formula (I), wherein when p=0, then L ischosen from linear and branched C₁-C₁₆ hydrocarbon-based chains, whichcan form at least one 3- to 6-membered carbon-based ring, wherein atleast one carbon atom of the carbon-based chain is optionally replacedwith an entity chosen from oxygen, nitrogen and sulfur atoms, and fromSO₂ groups, and further wherein the carbon atoms of the chain areoptionally substituted, independently of each other, with at least onehalogen atom; with the proviso that L does not comprise a peroxide bondor diazo or nitroso radicals, wherein when p=1, then L is chosen fromsaturated and unsaturated, linear and branched C₁ -C₁₆ hydrocarbon-basedchains, which can form at least one 3- to 6-membered carbon-based ring,wherein at least one carbon atom of the carbon-based chain is optionallyreplaced with an entity chosen from oxygen, nitrogen and sulfur atoms,and from SO₂ groups; with the proviso that L does not comprise aperoxide bond or diazo or nitroso radicals, R₃, R₄, R₅, R₆, R₇, R₉, R₁₀,R₁₁, R₁₂, R₁₃, R₁₄, R₁₅, R₁₆, R₁₇ and R₁₈, which may be identical ordifferent, are chosen from hydrogen atoms, saturated and unsaturated,linear and branched C₁-C₁₆ hydrocarbon-based chains, which can form atleast one 3- to 6-membered carbon-based ring, wherein at least onecarbon atom of the carbon-based chain is optionally replaced with anentity chosen from oxygen, nitrogen and sulfur atoms, and from SO₂groups, and the carbon atoms of the chain are optionally substituted,independently of each other, with at least one halogen atom; and withthe proviso that R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂, R₁₃, R₁₄, R₁₅,R₁₆, R₁₇ and R₁₈ do not comprise a peroxide bond or diazo or nitrosoradicals, R₃ with R₄, R₇ with R₉, R₁₀ with R₁₁, R₁₂ with R₁₃ and R₁₅with R₁₆ can optionally form a carbon-based aromatic ring, R₁, R₂ and R₈are chosen from linear and branched C₁-C₈ alkyl radicals optionallysubstituted with at least one radical chosen from hydroxyl, C₁-C₂alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyland sulfonic radicals; and optionally substituted phenyl radicals, and Xis chosen from organic and mineral anions; and at least one secondcompartment comprises an oxidizing composition.
 43. The method accordingto claim 1, wherein the dicationic diazo dyes of formula (I) are chosenfrom those of the following formulae:


44. The method according to claim 43, wherein the dicationic diazo dyesof formula (I) are chosen from those comprising a triazolium ring.
 45. Acomposition for dyeing human keratin fibers, comprising: a cosmeticmedium suitable for dyeing human keratin fibers, wherein said medium iswater or a mixture of water and at least one organic solvent suitablefor dyeing human keratin fibers, and at least one dicationic diazo dye,comprised in said medium, chosen from those of the following formulae: